Nonwoven webs or sheets such as those made of paper find extensive use in modern society in the context of household cleaning activity. Paper towels, for example, are a staple item of commerce which have long been used to wipe up liquid spills and to remove stains and/or soil from hard surfaces such as window glass, countertops, sinks, porcelain and metal fixtures, walls and the like, and from other surfaces such as carpeting or furniture.
Paper towels products which are especially useful for household cleaning have attributes which include relatively low density, high bulk, acceptable softness, high absorbency for both aqueous and nonaqueous liquids and acceptable strength and integrity, especially when wet. Prior art towel products having such attributes, and processes for their preparation, have been disclosed, for example, in Ayers, U.S. Pat. No. 3,905,863, issued Sep. 16, 1975; Ayers, U.S. Pat. No. 3,974,025, issued Aug. 10, 1976; Trokhan, U.S. Pat. No. 4,191,609, issued Mar. 4, 1980; Wells and Hensler, U.S. Pat. No. 4,440,597, issued Apr. 3, 1984; Trokhan, U.S. Pat. No. 4,529,840, issued Jul. 16, 1985; and Trokhan, U.S. Pat. No. 4,637,859, issued Jan. 20, 1987. Paper towels, such as those of the types described in the foregoing patents, are especially useful for absorbing and wiping up liquid spills from both hard surfaces and other surfaces such as furniture and carpets. Paper towel products, however, are also frequently used in combination with liquid cleaning solutions or solvents, to remove soil or stains from surfaces to which such soil or stains may be especially securely affixed. Such soil or stains, for example, may include food material on stove, oven, or cooking utensil surfaces, soap scum found in bathtubs and sinks, food and beverage stains on kitchen counters, ink or crayon markings on walls and furniture, and the like. These prior art materials typically require the consumer to clean soils and stains using a separate cleaning solution and wiping article, which involves a level of inconvenience.
To address this issue of convenience, pre-wetted wiping articles have been developed, particularly in the area of baby wipes. These pre-wetted wipes are typically kept in a dispenser and are typically soaked in a reservoir of a moistening solution. There is often a lack of consistency in terms of the moisture content of each of the wipes, and the wipes feel cold to the touch. Also, because the main purpose of such wipes is to clean, these wipes generally exhibit relatively poor post-cleaning absorbency.
Co-pending U.S. patent application Ser. No. 08/336,456 (hereafter "'456 application"), filed Nov. 9, 1994 by L. Mackey et al., and co-pending U.S. patent application Ser. No. 08/761,097, filed Dec. 5, 1996 by L. Mackey et al. (hereafter "'097 application") disclose and claim wet-like cleansing wipes that are especially useful in removing perianal soils. These cleansing wipes comprise a substrate material (e.g., a nonwoven) that is treated with a water-in-lipid emulsion. These wipes have a number of significant advantages over prior cleaning products, especially when in the form of wet-like cleansing wipes used to remove perianal soils. These articles release significant quantities of water during use for comfortable, more effective cleaning. The continuous lipid phase of the emulsion is sufficiently brittle so as to be easily disrupted by low shear contact (e.g., during the wiping of the skin) to readily release this internal water phase, but sufficiently tough at elevated temperatures where the lipid is melted to avoid premature release of the water phase during the rigors of processing. The continuous lipid phase of these articles is also sufficiently stable during storage so as to prevent significant evaporation of the internal water phase. The normal tensile strength and flushability properties of these articles are not adversely affected when treated with the high internal phase inverse emulsions of the present invention. As a result, users of these articles get comfortable, efficient, moist cleaning without having to change their normal cleaning habits. The application also indicates that the technology is readily useful with other wipes, including wipes for cleaning hard surfaces.
In spite of the significant improvements over prior cleansing wipes, the substrates (also referred to as "carriers") specifically described in the '456 application are generally highly absorbent materials that, upon shearing of the emulsion in use, retain a significant amount of fluid in the carrier. As a result, at least for certain end-uses (e.g., hard surface wipes), suboptimal fluid levels are delivered to the surface to be cleaned. As such, it is necessary to treat the substrate with additional amounts of emulsion to account for the level of fluid retained by the carrier.
Accordingly, in certain circumstances, it would be desirable to provide products for cleaning that offer the benefits provided by the cleansing wipes described in the co-pending '456 and '097 applications, but which require treatment with reduced levels of emulsion. In this regard, a carrier that retains a relatively small amount of fluid upon emulsion rupture, but which absorbs the fluid after the wiping process, is highly desirable.
Accordingly, it is an object of the present invention to provide cellulose-based wiping articles which (i) are initially dry to the touch, but are capable of delivering fluid during the wiping process, (ii) allow transfer of fluid released from the emulsion of the article to the item being cleaned, and (iii) have desirably high overall absorbent capacity for liquids and especially effective soil and stain removal performance.